Toxicant properties of nanoparticles are influenced by their dispersiveness, catalytic activity, aggregation and dissolution properties, which are determined by acid-base properties of the surface. This paper provides the experimental results of the research of surface acid-base characteristics for pH = 2.0...9.0, and takes into account their contribution to aggregative activity of Zn and ZnO nanoparticles in suspensions with pH = 4.0, 6.0, and 8.0. The maximum value of adsorption capacity can be expected in acid medium for Zn nanoparticles, and in base medium for ZnO nanoparticles. This study showed that when the value of pH is different from 6, suspension aggregative stability was strengthened or weakened for Zn and ZnO nanoparticles, respectively. The conclusion concerning the contribution of nanoparticles adsorption activity which is changed by surface acid-base characteristics to aggregative stability of particles of different compounds has been made.